A tearable tube has been used as a protective member for various articles until the articles are used. Among them, a tearable tube made of a fluorine resin has properties such as heat resistance, chemical resistance, water and oil repellency, non-adhesion, self-lubricity or the like which cannot be obtained with a tearable tube made of hydrocarbon-based synthetic resin.
Therefore, by using these properties, the tube has been used as a protective tube for precision equipment, electronic components or the like, or as a tube for introducing medical devices, which is used to introduce a catheter, a guide wire or the like into a body. The tube for introducing medical devices is unnecessary after a catheter or the like is introduced into the body, and also there is a management problem for maintaining the hygienic state. Thus, after the catheter is introduced into the body, the tube has to be withdrawn while being torn.
A tearable tube is required to securely protect the device mounted inside thereof, to be easily tearable without using a special device, and to maintain the properties possessed by the fluorine resin. The conventional tube in which a cut was made on its surface along with the longitudinal direction was not easily torn. Thus, in Japanese Patent Application Laid-Open No. 2008-20037, in order to easily tear without a need for an excessively cut portion, there has been proposed an extruded tube made of a fluorine resin which is obtained by extrusion molding a mixture of a tetrafluoroethylene resin and a fluorine resin having a low molecular weight. In order to coat the surface of a device such as a catheter with a fluorine resin, the heat-shrinkable tube made of a fluorine resin is needed to be heat-shrank by heating the tube after coating its surface. However, when the shrinkage of the heat-shrinkable tube is small, there is a problem that the close contact between the heat-shrinkable tube and the device is insufficient and also workability is deteriorated.